DNS servers Intermittently unavailable

[#1]

I am getting intermittent problems (3-4 times daily) to resolve host addresses. (Firefox would report Server not found, outlook would fail to reach the XChange server etcetera.)
When that is the case, I cannot ping either of the two DNS server. Rebooting the router helps, but sometimes more than one attempt is needed. This seems to be going on since a week or two. 
How to fix this?
I am using Netgear  DG 834G v2 on the most recent firmware. It  is set to use the DNS servers as assigned by ISP. For me, this comes down DNS Server:  212.159.6.10 and
212.159.6.9.

[#2]

change one of them to use Google DNS 8.8.8.8 and the other to 212.159.13.50 or 212.159.13.49

[#3]

This does seem to occur every few months, although I can't say I've noticed a problem this time as I built a caching DNS server for my home network to overcome this problem.
It might be worth reading the discussion and proposed solutions from last time this was an issue, see - http://community.plus.net/forum/index.php/topic,80867.msg678756.html
In the first instance I would do as Oldjim suggested, and set your router DNS to 8.8.8.8 (Google), and another one to try is 208.67.222.222 (OpenDNS).

[#4]

I found that my DG834v1 would do this after a period and that rebooting the router cleared it.
I significantly improved it by specifying the DNS servers on my PC rather than using the router.
(Since then I started using Treewalk which is a caching DNS server that runs on Windows)

[#5]

Ping to OpenDNS servers fails, too.
My netgear dg 834g V2 shows
Sun, 2002-09-08 12:00:51 - Initialize LCP.
Sun, 2002-09-08 12:00:51 - LCP is allowed to come up.
Sun, 2002-09-08 12:00:56 - CHAP authentication success
Sun, 2002-09-08 12:01:06 - Send out NTP request to time-g.netgear.com
Fri, 2010-04-09 05:31:05 - Receive NTP Reply from time-g.netgear.com
Fri, 2010-04-09 05:36:49 - Loss of synchronization :1
Note that was just after startup.
is it PN or The Router?

[#6]

It won't be us - sync is entirely between the exchange and yourself. It could be a fault on the line, it could be your router or it could be something plugged into your phone line at home possibly with a faulty filter.
Are the sync drops happening regularly, and do they still happen with the router plugged into the master phone socket with everything else unplugged from the line? If so the best thing would be to raise us a fault at http://faults.plus.net

[#7]

On the good side:

• Signal quality is much better with router connected to the master socket

On the bad side:

• ping time to bbc.co.uk still erratic


• sync still drops


• ping 212.159.13.49 can fail (100% packets lost ) while sync is perfectly OK
  

I will try again with a new router and improved wiring for the router.
Thank you for your advice. I might come back, if that won't cut the cheese.